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Challenge

At its plant in Dingolfing where aluminium front-axle beams for its 1 and 3 series cars are manufactured, BMW needed to produce the same output with fewer work stations and robots and less operating staff than for its 7 series.

Solution

YASKAWA first built the finished system in its own facilities to do a test run, and verified the basic functionality of the system in comprehensive tests. In addition, a twin station welding system was set up in Dingolfing where all the welding processes for the production of parts were optimised in co-operation with BMW. The practically identical production lines are highly automated and need very operators. The only manual production activity is that some individual parts are loaded by the operators on cassette belts, which does not influence the cycle time. Then the handling robots place all the parts in the appropriate welding fixtures. Here complex geometries with very narrow tolerances have to be loaded onto the fixture at high speed with repetitive accuracy. In order to accomplish this within the required cycle times, complex gripping systems that can hold the finished welded constructions as well as the individual parts are used. A special feature of the system layout is the flexibly designed welding cells. Depending on the requirement, either robot mounted torches are used, or the welding fixture is handled by the robot under fixed welding guns. Depending on the work piece, the welding processes are broken down into several stations, or are welded with several guns at the same time in order to achieve an even heat input and optimum time cycles. All welded seams of the entire front axle beam are inspected 100%. In addition, all the important parameters, such as the rim width and hole diameter, are measured exactly on the finished front axle beam with laser triangulation. Due to YASKAWA's multi robot technology, BMW has at present in Dingolfing up to three robots with 18 axes plus a turnover fixture that are connected to one controller. This allows the robots to work simultaneously at the multi-station table more easily. For example, if work is interrupted the robots stop at precisely defined positions at the same time. If the disturbance is corrected, the work step will be continued automatically at the place of interruption. Altogether in Dingolfing 78 welding robots and 20 handling robots (each six axes articulated robots) are grouped into 17 welding cells and three separate production lines for the BMW 1 and 3 series. The work cells also include various 2, 3 and 4 station positioners.

Results

The front axle beams are produced in three identical lines in 3 shifts per day. Six processing cells per line have been set up with a cycle time of 60 seconds. A cross member is made up of about 25 individual parts that are joined by aluminium gas  shielded welding in about 100 welding steps with a total seam length of 7.2 metres. Unique is that all production steps from the loading of the parts in the welding fixture through the welding process up to removing of finished modules are completed by robots.

Motoman welding robots at BMW

Fully automated robotic welding and handling


Customer

BMW

Product

Car front axle beams

Country

Germany

Industry

Automotive industry

Application

Aluminium MIG welding

Handling

System Components

MOTOMAN UP20 robots

MOTOMAN ES165N robots

Positioners

Contact

YASKAWA Europe GmbH

SHORT FACTS